In XDSL communication systems, there can be provisions made for adapting the rate at which data is communicated across the XDSL link. Rate Adaptive DSL (RADSL) is one example of such a system. In general, the data rate across an XDSL link is determined by the baud rate and the number of bits per symbol, or constellation. Thus, the data rate can be adjusted by adjusting either the baud rate or the size of the constellation.
Typically, conventional XDSL chip sets implement rate adaptive algorithms that provide a choice of rate based solely upon the signal-to-noise ratio (SNR). However, these schemes typically take too long to functions. Further, they often do not work because a given signal-to-noise ratio does not guarantee the desired performance (e.g., 10.sup.-7 bit error rate) at the desired rate. This is true in part because the chip set is assuming performance based upon relatively constant noise, when, in fact, real world physical connections do not typically experience constant patterns of noise. Thus, the conventional rate adaptive algorithms are incorrect on some types of noise models and do not accurately select the appropriate rate.